The present invention relates to the installation of a valve in the interior of a tank such as a float operated vent valve in the interior of a fuel tank, for example, a motor vehicle fuel tank, where the valve serves the purpose of controlling venting of fuel vapors from the tank.
In motor vehicle fuel tank systems, it is required to control the emissions of fuel vapor from the tank, particularly during refueling. Currently, production passenger car and light truck vehicles burning gasoline fuel have vapor vent lines from the tank connected to a storage container such as a canister filled with carbonaceous material for adsorption of the vapors during periods of vehicle engine shutdown, and for subsequent purge during vehicle engine operation.
Heretofore, fuel vapor vent valves for motor vehicle fuel tanks have been installed in the upper wall of the tank through an access opening in the tank provided for this purposes with a portion of the valve body or housing extending exteriorly of the tank and a portion with the float and float operated valve therein extending through the access opening into the interior of the tank.
The access opening for a fuel tank vapor vent valve must necessarily be at the highest point of the upper wall of the tank in order to be assured of being in the vapor dome within the tank. Thus, the access opening required for the vapor vent valve must be separately located from the access opening provided for installation in the tank of the float operated fuel level transducer or fuel level signal xe2x80x9csenderxe2x80x9d as such devices are often called. Such an arrangement thus requires attaching and sealing of the valve body about the separate access opening in the tank.
Currently many production motor vehicle tanks are formed of non-metallic material, such as molded plastic, of a composition having desired mechanical properties for robustness in service and mounting of the tank. This presents the problem of permeation of the vapors through the plastic wall of the tank where the material chosen for its mechanical properties is not impervious to the fuel vapors. The problem of vapor permeation through the tank wall has resulted in forming the tank with a barrier layer of relatively fuel impervious material in the wall of the tank which is otherwise formed of different more permeable material having the desired mechanical properties. This construction has presented problems in providing a fuel impervious seal about the vent valve body and the tank wall when a separate access opening for a vent valve is cut in the vapor barrier layer.
It has proven to be prohibitively costly and troublesome to attach the valve body to the tank wall by separate fasteners disposed about a sealing member for sealing about the separate access opening. Heretofore, in order to eliminate the costly use of separate fasteners, portions of the valve body have been formed of plastic material weldable to the tank wall material by any suitable weldment technique, as, for example, hot plate welding or spin welding.
However it has been found that the access opening in the vapor barrier layer of the tank wall provides a path for vapors to penetrate the more permeable material of the valve and tank wall and escape to the atmosphere.
The foregoing expediencies employed for providing a separate access opening in the tank for mounting a fuel vapor vent valve in the tank have proven to be difficult and quite costly during the manufacture and assembly of the tank prior to installation on the motor vehicle.
It has thus been desired to provide a way or means of installing the valve on the interior of the tank without separate fasteners or weldment and in a manner which maintains the integrity of the fuel vapor impervious barrier layer in the tank wall and eliminates the need for a separate access opening in the tank wall for installation of the valve.
The present invention provides a technique for mounting a valve on the interior of a tank wall without the need for a separate access opening through the tank wall and without the need for fasteners or weldment. The invention relates particularly to mounting of a vapor vent valve on the interior of the upper wall of a fuel tank without the need for a separate access opening for the vapor vent valve and thus breaking of the fuel vapor barrier layer provided in a non-metallic tank wall.
The present invention provides a deflectable mounting member extending from a mounting portion the valve body which member is deflected when inserted in an interiorly formed recess in the tank wall. The periphery of the deflectable member frictionally engages the recess to retain the valve therein. A guide member is provided on the mounting portion, spaced from the deflectable member, and likewise extending outwardly from the mounting portion of the valve body and the guide member enters into the recess upon insertion of the deflectable member. The guide member contacts the inner surface of the recess and prevents lateral movement of the deflectable member so as to prevent removal of the deflectable member from its engagement with the recess. In the preferred embodiment, the deflectable member comprises a relatively thin disc having voids therein and preferably the voids comprise radially extending slots which form deflectable finger-like portions therebetween. In the preferred embodiment, the guide member also has a relatively thin disc-like configuration but slides freely into the mounting recess. The present invention thus enables the valve body mounting portion, deflectable member and guide to be formed in a one-piece construction, preferably by molding of plastic material.